When people start to pay attention to what and how much they eat, there occurs one question. When should we weigh products? Before thermal treatment or after? What's the difference? And how can we count these products in our demand? Because of boiling, stewing or roasting, products change their weight. It happens because they decrease or increase the amount of water in their content.
Rice, groats or noodles increase their weight during boiling. 100g of dry rice weighs about 250g after boiling. 100g of dry groats weighs about 300g after boiling. When you boil rice for too long, it will be overcooked, and the weight will change from 100g to about 300g. When you boil al dente noodles, it will weigh less than when it's cooked longer. But still, such rice or groats will have the same calorific content and macro nutrients as 100g of dry product.
Chicken breast loses about 33% of its mass during thermal treatment. Therefore, 100g of raw chicken breast will weigh about 70g after cooking. The amount of weight that decreases during thermal treatment depends on the amount of water in the meat and the kind of thermal treatment you choose. Steamed chicken breast will probably lose less water than roasted one. In some cases 100g of raw meat will weigh 70g after cooking, in other cases it will be 80g. However, there still will be the same amount of protein and fat as in raw meat. Protein does not evaporate from it during cooking. 100g of chicken breast will still contain about 22g of protein.
100g of groats boiled by me will not necessarily be the same amount as 100g of groats cooked by somebody else. It's enough to cook it 5 minutes longer. The same thing is with chicken breast – 100g of boiled meat on one day doesn't have to be equal to 100g of chicken breast boiled on another day.
That's also why you should weigh food before thermal treatment
If you want to estimate the calorific content of the eaten meal, and you didn't weigh the products before, you may count it, exceptionally, on the basis of cooked products. However, you should remember about doing it the right way. Majority of products in nutrition diaries are raw. So, you have to choose the products signed roasted/boiled, or estimate the weight of raw product on the basis of the product after thermal treatment. For example, 140g of boiled cicken breast is about 200g of raw chicken breast.
If you count the calorific content of the meals by weighing the processed products, and choosing the raw ones, your calculations will be wrong. For example, 100g of boiled buckwheat groats is about 110kcal (1/3 of the bag), and not 332kcal (the calorific content of raw groats).
To sum up, you should weigh the products before thermal treatment. This issue seems trivial, but it causes a lot of doubts in many people. I hope that after reading this article there are less of them.